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Platte River Status: A fairly common migrant and uncommon and local summer resident. Occurrence dates at the Mormon Island Crane Meadows, Hall County, extend from 15 February to 26 September. Tout (1947) found gadwall only as a migrant in Lincoln County, present 5 March to 5 July, and 6 September to 9 November. Rosche (1979) considered gadwall a migrant and winter visitor in the lower North Platte River Valley, present 20 August to 4 June.

Breeding Range: A rare summer resident in the Sandhills and in the Rainwater Basin area of the Eastern Plain; accidental elsewhere.

Breeding Population: The population in 1979-1980 was estimated at 1,063 breeding pairs. Only seven gadwall pairs were present on Waterfowl Production Areas in the Rainwater Basin area in 1983 (USFWS files).

Habitat: We found a mean density of 6.4 pairs per km² on prairie wetlands. In the Platte River Valley, gadwall during the nesting season are most frequently found on semi-open seasonal wetlands. One gadwall pair on the North Platte, Lincoln County, sewage lagoon 29 May 1979 suggests that at least limited use is made of that artificial habitat type. Faanes (1982) found greatest densities of nesting gadwall on a central North Dakota study area were on brackish or saline wetlands. Kantrud and Stewart (1972) reported that highest densities in North Dakota occurred on temporary wetlands (54.3 pairs/km²) and seasonal wetlands (38.8 pairs/km²). Fifty-one percent of gadwall nests studied by Duebbert and Lokemoen (1980) in North Dakota were in herbaceous cover from 30 to 60 cm tall; 47% were in cover >60 cm tall. Vegetation <20 cm tall is considered too short for nest concealment (Martz 1967).

Effect of Habitat Alteration: De-watering of the Platte River system for agricultural production, drainage of wetlands in the Rainwater Basin area, and conversion of wet meadows and low prairie to cropland have adversely impacted nesting and brood-rearing habitat for this species.

Nesting Data: We have one confirmed record of nests or eggs from the study area. Lingle observed a hen that was probably nesting at the Mormon Island Crane Meadows, Hall County, during 25 May to 11 June 1980. A hen with a brood was found in a seasonal wetland on the Taylor Ranch in Hall County on 22 July 1985. Egg dates in North Dakota extend from 18 May to 10 August (Stewart 1975).